Background: Intraoperative nerve stimulation (IONS) could potentially reduce the incidence of recurrent laryngeal nerve (RLN) injury in thyroidectomy. The current study aimed at demonstrating the technical feasibility of using IONS in gasless, transaxillary endoscopic thyroidectomy (GTET) and robotic-assisted thyroidectomy (RAT) with conventional nerve stimulator probe and comparing the overall accuracy between two different nerve stimulation techniques, namely the direct RLN stimulation and the indirect stimulation via the vagus nerve (VN group), in predicting postoperative RLN function.
Methods: From 2009 to 2010, 60 (17.1%) patients underwent endoscopic thyroidectomy using IONS. Thirty-three (55.0%) patients had direct intraoperative RLN stimulation (RLN group), whereas 27 (45.0%) patients had stimulation to the VN (VN group). Total number of nerves at risk was 76. The results of IONS were confirmed by the postoperative vocal cord movement on laryngoscopy.
Results: Patient demographics, surgical indications, resection type, size of dominant nodule, excised gland weight, and final pathology were similar between the two groups. The number of vocal cord palsies in the RLN and VN groups was 3 (7.3%) and 2 (5.7%), respectively. Compared with the VN group, the RLN group had a significantly lower percentage of true negatives (78.0% vs. 94.3%, P=.045) and higher percentage of false positives (14.6% vs. 0.0%, P=.018). Overall accuracy was higher in the VN group.
Conclusions: The current study demonstrated the technical feasibility of using conventional open-nerve stimulator probe in both GTET and RAT. Indirect stimulation via the VN produced more reliable and accurate IONS test results than direct RLN stimulation.